Long term evolution (LTE) of WCDMA 3G cellular networks pertains to UMTS beyond 3GPP Release 7. Another term used to express LTE is evolved (Universal Terrestrial Radio Access” i.e.) “evolved (UTRA)” (E-UTRA).
3GPP Release 6 uses a random access channel (RACH) procedure for initial uplink access. The RACH procedure defines a preamble burst handshake followed by a short, preconfigured message. Random access based on an uplink grant channel has been proposed for E-UTRA.
Hereafter, a wireless transmit/receive unit (WTRU) includes but is not limited to a user equipment (UE), mobile station, fixed or mobile subscriber unit, pager, or any other type of device capable of operating in a wireless environment. When referred to hereafter, a base station includes but is not limited to a Node-B, site controller, access point (AP) or any other type of interfacing device in a wireless environment.
A general problem with uplink access protocols is that one access protocol may not work in all cases. For example, no single access protocol supports all traffic types equally well. A Telnet application is highly bursty, has a low data rate, and is highly delay sensitive—the current 3GPP RACH procedure might work very well for this type of application. On the other hand, web browsing requires more bandwidth in the uplink, and is not as sensitive to delay as Telnet, whereby an alternate access protocol may prove superior for this application. Another example is that the best protocol may vary as a function of cell load. Combining this with existing considerations in UTRA, there is a need to define an uplink access framework with all of the following attributes:                A WTRU should be able to use multiple uplink access protocols.        The initial uplink access burst should contain few (or no) information bits to maximize decoding performance while minimizing needed bandwidth (the RACH preamble in the current standard has no information bits).        Likewise, the response to the initial uplink access burst should contain few (or no) information bits (the Acquisition Indicator Channel (AICH) message in the current standard has a single information bit, namely, the acquisition indicator bit).        